Cable conductor shields have been utilized in multilayered power cable construction for many years. These shields provide a layer of intermediate conductivity between the conductor and the cable insulation. Typical shield compositions contain ethylene vinyl acetate copolymer having a high vinyl acetate content, i.e., in the 18 to 20 percent by weight range, carbon black, a crosslinking agent, and other conventional additives. While these compositions have been found to be commercially acceptable, they are lacking in one respect, i.e., they are subject to marring when passed through conventional extrusion equipment used to apply the shield. A marred (or damaged) conductor shield can be expected to have a major negative impact on cable performance and expected life. The damage to the conductor shield can range from a minor flattening to breaks in the shield where portions are gouged out. These defects result in an imperfect interface with the cable insulation.
The damage may occur, for example, in a tandem extrusion line where the conductor shield comes in contact with the hot guider of the insulating extruder. Common causes of the problem are misalignment of the extrusion equipment where the cable enters the guider; sharp corners or scratches on the uider; and/or vibration in the line.